Partner Fund Management Has Confidence In Blueprint Medicines Corp (BPMC)

Chris James’ Partner Fund Management revealed a 5.1% position in Blueprint Medicines Corp (NASDAQ:BPMC) last week. At the end of 2015 Chris James’ hedge fund owned a million shares of the biotech company. Last week’s filings indicated that Partner Fund Management boosted its position by about 37% during the first quarter probably taking advantage of the decline in share prices. Blueprint Medicines Corp was quite popular among healthcare hedge funds such as BVF, Visium, RA Capital, and Perceptive Advisors. Hedge funds tracked by Insider Monkey collectively owned nearly 30% of BPMC’s outstanding shares at the end of 2015.

Here are the details of Partner Fund Management’s recent purchases:

Ownership Summary Table

Name Sole Voting Power Shared Voting Power Sole Dispositive Power Shared Dispositive Power Aggregate Amount Owned Power Percent of Class
Partner Fund Management 0 1,359,946 0 5.0%
Partner Fund Management GP 0 1,359,946 0 5.0%
Partner Investment Management 0 18,788 0 0.1%
Partner Investment Management GP 0 18,788 0 0.1%
Brian D. Grossman 0 1,378,734 0 5.1%
Christopher M. James 0 1,378,734 0 5.1%

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Page 1 of 13 – SEC Filing

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C.  20549
SCHEDULE 13G
(Rule 13d-102)
Information Statement Pursuant to Rules 13d-1 and 13d-2
Under the Securities Exchange Act of 1934
(Amendment No.      )*
Blueprint Medicines Corporation
(Name of Issuer)
Common stock, par value $0.001 per share
(Title of Class of Securities)
09627Y109
(CUSIP Number)
March 18, 2016
Date of Event Which Requires Filing of the Statement

Check the appropriate box to designate
the rule pursuant to which this Schedule is filed:

¨ Rule 13d-1(b)
x Rule 13d-1(c)
¨ Rule 13d-1(d)

*The remainder of this cover page shall
be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for
any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder
of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of
1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions
of the Act (however, see the Notes).

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Page 2 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 2 of 13 Pages

1.

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Partner Fund Management, L.P.

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)    ¨

 

(b)    x

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

 

1,359,946 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX
IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES

CERTAIN SHARES                                                                                                                            ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

5.0%1

12.

TYPE OF REPORTING PERSON

IA; PN

1 The percentages reported in this Schedule 13G are based
upon 27,201,271 shares of common stock outstanding as of February 29, 2016 according to the Form 10-K filed by the issuer with
the Securities and Exchange Commission on March 11, 2016. All of the other numbers and percentages reported in this Schedule 13G
are as of 9:00 a.m. (PT) on the date of filing.

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Page 3 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 3 of 13 Pages

1.

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Partner Fund Management GP, LLC

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)    ¨

 

(b)    x

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

 

1,359,946 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX
IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES

CERTAIN SHARES                                                                                                                            ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

5.0%

12.

TYPE OF REPORTING PERSON

OO

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Page 4 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 4 of 13 Pages

1.

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Partner Investment Management, L.P.

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)    ¨

 

(b)    x

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

 

18,788 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX
IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES

CERTAIN SHARES                                                                                                                            ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

0.1%

12.

TYPE OF REPORTING PERSON

IA; PN

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Page 5 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 5 of 13 Pages

1.

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Partner Investment Management GP, LLC

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)    ¨

 

(b)    x

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

Delaware

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

 

18,788 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX
IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES

CERTAIN SHARES                                                                                                                            ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

0.1%

12.

TYPE OF REPORTING PERSON

OO

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Page 6 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 6 of 13 Pages

1.

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Brian D. Grossman

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)    ¨

 

(b)    x

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

U.S. Citizen

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

 

1,378,734 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX
IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES

CERTAIN SHARES                                                                                                                            ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

5.1%

12.

TYPE OF REPORTING PERSON

IN

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Page 7 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 7 of 13 Pages

1.

NAME OF REPORTING PERSON

S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

Christopher M. James

2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP

(a)    ¨

 

(b)    x

3.

SEC USE ONLY

4.

CITIZENSHIP OR PLACE OF ORGANIZATION

U.S. Citizen

NUMBER OF

SHARES

BENEFICIALLY

OWNED BY

EACH

REPORTING

PERSON

WITH

5.

SOLE VOTING POWER

0

6.

SHARED VOTING POWER

 

1,378,734 shares

7.

SOLE DISPOSITIVE POWER

0

8.

SHARED DISPOSITIVE POWER

See Row 6 above

9.

AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

See Row 6 above

10.

CHECK BOX
IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES

CERTAIN SHARES                                                                                                                            ¨

11.

PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

5.1%

12.

TYPE OF REPORTING PERSON

IN

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Page 8 of 13 – SEC Filing

 

CUSIP No. 09627Y109 13G Page 8 of 13 Pages

 

Item 1(a) Name of Issuer
Blueprint Medicines Corporation
Item 1(b) Address of Issuer’s Principal Executive Offices
38 Sidney Street, Suite 200, Cambridge, Massachusetts  02139
Item 2(a) Name of Person Filing
This Schedule 13G is being jointly filed by Partner Fund Management, L.P. (“PFM”), Partner Fund Management GP, LLC (“PFM-GP”), Partner Investment Management, L.P. (“PIM”), Partner Investment Management GP, LLC (“PIM-GP”), Brian D. Grossman (“Grossman”) and Christopher M. James (“James” and, collectively with PFM, PFM-GP, PIM, PIM-GP and Grossman, the “Reporting Persons”) with respect to shares of common stock of the above-named issuer owned by PFM Healthcare Master Fund, L.P., a Cayman Islands limited partnership (“HCM”), PFM Healthcare Opportunities Master Fund, L.P., a Cayman Islands limited partnership (“HCOPP”), PFM Healthcare Principals Fund, L.P., a Delaware limited partnership (“HCP”), PFM Healthcare Emerging Growth Master Fund, L.P., a Cayman Islands limited partnership (“HEGM”), and PFM Oncology Opportunities Master Fund, L.P., a Cayman Islands limited partnership (“ONCOPP” and, collectively with HCM, HCOPP, HCP and HEGM, the “Funds”).
PFM is the investment advisor for HCM, HCOPP, HEGM and ONCOPP.  PIM is the investment advisor for HCP.  PFM-GP and PIM-GP are, respectively, the general partners of PFM and PIM.  Grossman is the portfolio manager for the health care strategy for the Funds.  James is the chief investment officer for PIM and PFM and member manager of PFM-GP and PIM-GP.
The filing of this statement shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any securities covered by the statement other than the securities actually owned by such person (if any).
Item 2(b) Address of Principal Business Office
The address of the principal business office of each of the Reporting Persons is c/o Partner Fund Management, L.P., 4 Embarcadero Center, Suite 3500, San Francisco, CA  94111.
Item 2(c) Citizenship
Each of PFM and PIM is organized as a limited partnership under the laws of the State of Delaware.  Each of PFM-GP and PIM-GP is organized as a limited liability company under the laws of the State of Delaware.  Each of Grossman and James is a U.S. citizen.
 
Item 2(d) Title of Class of Securities
Common stock, $0.001 par value
Item 2(e) CUSIP Number
09627Y109

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Page 9 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 9 of 13 Pages
Item 3 If this statement is filed pursuant to Rules 13d-1(b), or 13d-2(b) or (c), check whether the person filing is a:
(a) ¨ Broker or dealer registered under Section 15 of the Exchange Act;
(b) ¨ Bank as defined in Section 3(a)(6) of the Exchange Act;
(c) ¨ Insurance company as defined in Section 3(a)(19) of the Exchange Act;
(d) ¨ Investment company registered under Section 8 of the Investment Company Act;
(e) ¨ An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);
(f) ¨ An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F);
(g) ¨ A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G);
(h) ¨ A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act;
(i) ¨ A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act;
(j) ¨ Group, in accordance with Rule 13d-1(b)(1)(ii)(J).

If filing as
a non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J), please specify the type of institution: ____________.

 

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Page 10 of 13 – SEC Filing

 

CUSIP No. 09627Y109 13G Page 10 of 13 Pages

 

Item 4 Ownership
A. Partner Fund Management, L.P. and Partner Fund Management
GP, LLC
(a) PFM and PFM-GP may be deemed to beneficially own 1,359,946 shares of Common Stock.
(b) The number of shares PFM and PFM-GP may be deemed to beneficially own constitutes approximately 5.0%
of the Common Stock outstanding.
(c) Number of shares as to which such person has:
(i) sole power to vote or to direct the vote: 0
(ii) shared power to vote or to direct the vote: 1,359,946
(iii) sole power to dispose or to direct the disposition of: 0
(iv) shared power to dispose or to direct the disposition of: 1,359,946
B. Partner Investment Management, L.P. and Partner Investment Management GP, LLC
(a) PIM and PIM-GP may be deemed to beneficially own 18,788 shares of Common Stock.
(b) The number of shares PIM and PIM-GP may be deemed to beneficially own constitutes approximately 0.1%
of the Common Stock outstanding.
(c) Number of shares as to which such person has:
(i) sole power to vote or to direct the vote: 0
(ii) shared power to vote or to direct the vote: 18,788
(iii) sole power to dispose or to direct the disposition of: 0
(iv) shared power to dispose or to direct the disposition of: 18,788

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Page 11 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 11 of 13 Pages
C. Brian D. Grossman
(a) Grossman may be deemed to beneficially own 1,378,734 shares of Common Stock.
(b) The number of shares Grossman may be deemed to beneficially own constitutes approximately 5.1% of
the Common Stock outstanding.
(c) Number of shares as to which such person has:
(i) sole power to vote or to direct the vote: 0
(ii) shared power to vote or to direct the vote: 1,378,734
(iii) sole power to dispose or to direct the disposition of: 0
(iv) shared power to dispose or to direct the disposition of: 1,378,734
D. Christopher M. James
(a) James may be deemed to beneficially own 1,378,734 shares of Common Stock.
(b) The number of shares James may be deemed to beneficially own constitutes approximately 5.1% of the
Common Stock outstanding.
(c) Number of shares as to which such person has:
(i) sole power to vote or to direct the vote: 0
(ii) shared power to vote or to direct the vote: 1,378,734
(iii) sole power to dispose or to direct the disposition of: 0
(iv) shared power to dispose or to direct the disposition of: 1,378,734

 

Item 5 Ownership of Five Percent or Less of a Class
If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than 5 percent of the class of securities, check the following ¨.
Item 6 Ownership of More than Five Percent on Behalf of Another Person
Not Applicable
Item 7 Identification and Classification of the Subsidiary which Acquired the Security Being Reported on by the Parent Holding Company
See Item 2 above
Item 8 Identification and Classification of Members of the Group
Not Applicable

 

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Page 12 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 12 of 13 Pages
Item 9 Notice of Dissolution of Group
Not Applicable
Item 10 Certification
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

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Page 13 of 13 – SEC Filing

CUSIP No. 09627Y109 13G Page 13 of 13 Pages

After reasonable inquiry
and to the best of its knowledge and belief, the undersigned certify that the information set forth in this statement is true,
complete and correct.

Dated this 28th day of March, 2016.

PARTNER FUND MANAGEMENT, L.P. PARTNER FUND MANAGEMENT GP, LLC
By: Partner Fund Management GP, LLC By: /s/ Darin Sadow
its general partner Darin Sadow, Authorized Signatory
By: /s/ Darin Sadow
Darin Sadow, Authorized Signatory
PARTNER INVESTMENT MANAGEMENT, L.P. PARTNER INVESTMENT MANAGEMENT GP, LLC
By: Partner Investment Management GP, LLC, By: /s/ Darin Sadow
its general partner Darin Sadow, Authorized Signatory
By: /s/ Darin Sadow
Darin Sadow, Authorized Signatory
BRIAN D. GROSSMAN CHRISTOPHER M. JAMES
By: /s/ Darin Sadow By: /s/ Darin Sadow
Darin Sadow, attorney-in-fact* Darin Sadow, attorney-in-fact**
* Darin Sadow is signing on behalf of Brian Grossman as attorney-in-fact pursuant to a power of attorney
dated August 4, 2011, and incorporated by reference herein. The power of attorney was filed as an attachment to a filing by certain
of the Reporting Persons on Schedule 13G for K-V Pharmaceutical Company on August 5, 2011.
** Darin Sadow is signing on behalf of Christopher M. James as attorney-in-fact pursuant to a power of
attorney dated August 4, 2011, and incorporated by reference herein. The power of attorney was filed as an attachment to a filing
by certain of the Reporting Persons on Schedule 13G for K-V Pharmaceutical Company on August 5, 2011.

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